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81.
82.
A new circularly polarized (CP) Raman spectrometer is described that demonstrates simultaneous acquisition of all four forms of circular polarization Raman optical activity (ROA). The instrument is a design extension of a commercially available back scattering circular polarization (SCP) ROA spectrometer. Circular polarization of the incident beam is introduced with a quarter‐wave plate, and a half‐wave plate alternately positioned in and out of the beam controls the modulation between right circular polarization (RCP) or left circular polarization (LCP) states. Combining this modulation with the simultaneous detection of RCP and LCP scattered Raman radiation allows the measurement of incident circular polarization (ICP), SCP, in‐phase dual circular polarization(DCPI) and out‐of‐phase DCPII‐ROA. In addition, three different forms of backscattered Raman spectra, namely unpolarized, highly polarized, and depolarized Raman spectra, as well as a degree of circularity spectrum are obtained. The performance of the new all‐CP ROA spectrometer is evaluated with neat α‐pinene and aqueous hen lysozyme solution. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
83.
Dissolution studies on lysozyme crystals were carried out since the observed dissolution pattern look different from non‐protein dissolved crystals. The Tetragonal, High Temperature and Low Temperature Orthorhombic morphologies, crystallized using sodium chloride, were chosen and the influence of different pH, salt and protein concentration on their dissolution was investigated. An increase in pH and/or salt concentration can modify the dissolution behaviour. The pattern of the crystals during the dissolution process will, therefore, develop differently. Frequently a skeleton like crystal pattern followed by a falling apart of the crystals is observed. The multi‐component character of the lysozyme crystal (protein, water, buffer, salt) as well as “solvatomorphism” gives first insights in the phenomena happening in the dissolution process. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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85.
Chang Kui SUN Yu Zhen ZHANG Ming CHEN 《中国化学快报》2006,17(11):1469-1472
A novel lysozyme namedβ-1, 4-N, 6-O-diacetylmuramidase R2 was purified and characterized from Streptomyces griseus. The molecular weight of the enzyme was determined by MALDI-TOF-MS as 23.5 kDa. The N-terminal amino acid sequence was DTSGVQGIDVS-HWQG.Chemical modification ofβ-1, 4-N, 6-O-diacetylmuramidase R2 indicated that sulfhydry1 group and carbamidine of arginine residues are not essential for the activity of the enzyme, but lysine residues and imidazole of histidine residues are essential for the activity. The number of essential tryptophan and carboxyl groups was found that only one tryptophan residue and three carboxyl groups in the active site. 相似文献
86.
通过异硫氰酸荧光素标记的溶菌酶(FITC-Lys)和聚乙烯亚胺修饰的荷正电纳米金粒子(PEI-AuNPs)与细菌结合,构建了一个基于荧光共振能量转移(FRET)的平台用于广谱细菌检测。待检样本中存在细菌时,荷正电的FITC-Lys(能量供体)通过与细胞壁肽聚糖的识别作用和静电作用与细菌结合,荷正电的PEI-AuNPs(能量受体)也通过静电作用与细菌结合,使能量供体和受体之间的距离缩短,荧光猝灭,显示出低荧光强度的FRET“开”的信号读出模式。采用水热法合成了PEI-AuNPs,通过紫外光谱、透射电镜、激光粒度仪等对PEI-AuNPs进行了表征。结果表明,PEI-AuNPs在526.5 nm处有最大紫外吸收,直径约为9.6 nm,荷正电。该方法可对10种细菌(如金黄色葡萄球菌、肺炎链球菌、粪肠球菌、表皮葡萄球菌、李斯特菌、大肠杆菌、鼠伤寒沙门氏菌、甲型副伤寒沙门氏菌、副溶血弧菌和铜绿假单胞菌)进行检测。考察了实际样本(以牛奶和果汁为例)中可能的干扰组分对检测的干扰情况。结果表明,将样本稀释10倍后,样本中蛋白、离子等不会对分析结果产生干扰。该研究构建的广谱细菌检测方法,对于致病菌的防控具有积极意义。 相似文献
87.
Ushasi Pramanik Anju Ajayan Kongasseri Shashi Shekhar Ashwin Mathew Rahul Yadav Saptarshi Mukherjee 《Chemphyschem》2021,22(17):1745-1753
The endocrine disrupting compound Bisphenol and its analogues are widely used in food packaging products and can cause serious health hazards. The protein, Lysozyme (Lyz), showing anti-microbial properties, is used as a “natural” food and dairy preservative. Herein, we explored the interaction between Lyz and Bisphenol S (BPS) by multi-spectroscopic and theoretical approaches. Lyz interacts with BPS through static quenching, where hydrophobic force governed the underlying interaction. Molecular docking results reveal that tryptophan plays a vital role in binding, corroborated well with near UV-CD studies. A decrease in the radius of gyration (from 1.43 nm to 1.35 nm) of Lyz substantiates the compactness of the protein conformation owing to such an interaction. This structural alteration experienced by Lyz may alter its functional properties as a food preservative. Consequently, this can degrade the quality of the food products and thereby lead to severe health issues. 相似文献
88.
89.
G. Rangel‐Porras P. Rangel‐Rivera H. Pfeiffer‐Perea P. Gonzalez‐Muñoz 《Surface and interface analysis : SIA》2015,47(1):135-141
The aim of this work is to study the difference in the characteristics of commercial clay after the inclusion of two proteins. Bovine serum albumin and egg white lysozyme were immobilized on the structure of commercial montmorillonite, which was previously treated with a hydrochloric acid solution. Studies were carried out at two different concentrations, fixing the pH to ensure the charge of biomolecules and clay surface. Acid‐treated clay containing proteins was characterized by X‐ray diffraction, Fourier transformed infrared spectroscopy, thermogravimetric analysis, and nitrogen adsorption at 77 K. The powders showed similar thermal behavior after the inclusion of proteins but with variations in the amount of mass loss in each sample. Moreover, changes in the surface characteristics of the final solid were observed, depending on both the concentration and the nature of the incorporated protein. The differences observed in the acid‐treated clay characteristics after the inclusion of each type of protein are discussed. The characterization of materials after the inclusion of protein molecules can be useful to understand the adsorption mechanism of biomolecules on solid surfaces. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
90.
Approaches for improving the performance of near-infrared diffuse reflectance spectroscopy (NIRDRS) have been extensively studied. The silver mirror was found to be a substrate to enhance the detection ability of this technique. For further optimization of the method, experimental and chemometric efforts were made in this study. Lysozyme samples of different concentrations were spotted on the silver mirror for measuring the spectra. Low-resolution spectra with repeated measurements were used for increasing the signal-to-noise ratio, and the chemometric methods of variable selection and nonlinear modeling were used to make the quantitative model more effective and accurate. The results show that the quality of the spectra was improved and a satisfactory quantitative model was obtained after optimization. The maximum deviation for the prediction samples is only 2.98?µg, which is much lower than the reported values in previous papers. Significant advances were obtained for NIRDRS for trace analysis. 相似文献